Fig. 8.  Group data showing the effects of bilateral section of carotid sinus nerves (CSN) on the cardiorespiratory responses to the brief hypoxia (A ) or hypercapnia (B ). Note: All the cardiorespiratory variables during hypoxia or hypercapnia were significantly changed with the exception that V^Eand V^Tduring hypoxia exposure were not significantly different from baseline after sectioning the CSN. n = 10; data are presented as means ± SE; P  values less than 0.05 are presented exactly and those more than 0.82 are not presented. f = breath frequency; HR = heart rate; MBP = mean blood pressure; V^E= minute ventilation; V^T= tidal volume.